Hematite
Iron oxide (Fe₂O₃)
The principal iron ore, a heavy iron oxide ranging from metallic silver-gray to earthy red, always leaving a tell-tale red-brown streak.
- Mohs hardness
- 5-6
- Color
- Steel-gray to black; reddish when earthy
- Type
- mineral
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Overview
Hematite is iron(III) oxide (Fe₂O₃) and the world's most important iron ore. It appears in two contrasting guises: a shiny, metallic steel-gray to black form, and a dull, earthy red form. In all cases it leaves a diagnostic reddish-brown streak, which is the source of its name (from the Greek for "blood").
This red coloring power makes hematite the pigment behind much of the red in soils, rocks, and even the surface of Mars. Polished metallic hematite has a bright, mirror-like sheen and a noticeable heft due to its high iron content.
It is mined in vast quantities and also popular as an inexpensive ornamental stone.
Formation & geology
Hematite forms in many settings. The most economically important are banded iron formations (BIFs)—ancient chemically precipitated sedimentary rocks deposited in early oceans billions of years ago.
It also forms by oxidation and weathering of iron-bearing minerals, in hydrothermal veins, and as a precipitate in lakes and hot springs. The earthy red variety often coats and cements other rocks, while "kidney ore" forms botryoidal (grape-like) masses.
Major deposits occur in Brazil, Australia, China, India, and the Lake Superior region (USA/Canada).
How to identify it
- Streak: The key test—hematite always leaves a reddish-brown to cherry-red streak on unglazed porcelain, even when the specimen looks black and metallic.
- Color & luster: Steel-gray to black with metallic luster, or dull brick-red when earthy.
- Hardness: 5-6; brittle. Heavier than most rocks (high specific gravity, ~5).
- Not magnetic: Pure hematite is, at most, weakly magnetic (unlike magnetite).
Look-alikes: Magnetite is strongly magnetic and has a black streak. Galena is softer, denser, and has a gray streak with cubic cleavage. The red streak reliably separates hematite from look-alikes.
Uses & significance
Hematite is the leading ore of iron, supplying the bulk of the world's steel production. Its earthy red form is a classic pigment (red ochre) used since prehistoric times in paints and cosmetics.
It is also a polishing compound ('jeweler's rouge') and a popular ornamental stone, cut into beads, cabochons, and carvings with a striking metallic shine. Most magnetic "hematite" jewelry is actually a synthetic magnetized material.
Metaphysically it is associated with grounding and protection—cultural belief, not science.
Frequently asked questions
Is hematite magnetic?
Natural hematite is only weakly magnetic at most. Strongly magnetic 'hematite' beads are usually a man-made magnetized ceramic, not true hematite.
Why does black hematite leave a red streak?
Regardless of its surface color, hematite is iron oxide that powders to fine red particles, so its streak on unglazed porcelain is reddish-brown.
Is hematite valuable?
As an ore it is hugely important economically, but specimens and ornamental pieces are inexpensive; value comes from fine crystals or rosettes.
How is hematite different from magnetite?
Magnetite is strongly magnetic with a black streak; hematite is weakly magnetic at most and leaves a diagnostic red-brown streak.
Hematite guides
In-depth guides for identifying, valuing, and understanding Hematite.
Hematite identified by the community
Real specimens identified with Rock Identifier.
